Improved memory allocation and configuration.
Memory is now allocated by the
NDB kernel to tables on a
page-by-page basis, which significantly reduces the memory
overhead required for maintaining
NDBCLUSTER tables. In
addition, the
MaxAllocate
configuration parameter now makes it possible to set the
maximum size of the allocation unit used for table memory.

Choice of fixed-width or variable-width columns.
You can control whether fixed-width or variable-width
storage is used for a given column of an
NDB table by employing of the
COLUMN_FORMAT specifier as part of the
column's definition in a CREATE
TABLE or ALTER
TABLE statement. In addition, the ability to
control whether a given column of an
NDB table is stored in memory
or on disk, using the STORAGE specifier
as part of the column's definition in a
CREATE TABLE or
ALTER TABLE statement. For
more information, see CREATE TABLE Syntax, and
ALTER TABLE Syntax.

Controlling management client connections.
The --bind-address cluster management
server startup option makes it possible to restrict
management client connections to
ndb_mgmd to a single host (IP address
or host name) and port, which can make MySQL Cluster
management operations more secure. For more information
about this option, see
Section 6.4, “ndb_mgmd — The MySQL Cluster Management Server Daemon”.

Micro-GCPs.
Due to a change in the protocol for handling of global
checkpoints (GCPs handled in this manner sometimes being
referred to as “micro-GCPs”), it is now
possible to control how often the GCI number is updated,
and how often global checkpoints are written to disk,
using the
TimeBetweenEpochs
and
TimeBetweenEpochsTimeout
configuration parameters. This improves the reliability
and performance of MySQL Cluster Replication.

Core online schema change support.
Support for the online ALTER
TABLE operations ADD COLUMN,
ADD INDEX, and DROP
INDEX is available. When the
ONLINE keyword is used, the
ALTER TABLE is noncopying,
which means that indexes do not have to be re-created,
which provides these benefits:

Single user mode is no longer required for
ALTER TABLE operations
that can be performed online.

Transactions can continue during
ALTER TABLE operations
that can be performed online.

Tables being altered online are not locked against
access by other SQL nodes.

However, such tables are locked against other operations
on the same SQL node for the
duration of the ALTER
TABLE. We are working to overcome this
limitation in a future MySQL Cluster release.

mysql.ndb_binlog_index improvements.
More information has been added to the
mysql.ndb_binlog_index table so that it
is possible to determine which originating epochs have
been applied inside an epoch. This is particularly useful
for 3-way replication. See
Section 8.4, “MySQL Cluster Replication Schema and Tables”, for
more information.

Epoch lag control.
The
MaxBufferedEpochs
data node configuration parameter provides a means to
control the maximum number of unprocessed epochs by which
a subscribing node can lag. Subscribers which exceed this
number are disconnected and forced to reconnect.

Fully automatic database discovery.
It is no longer a requirement for database autodiscovery
that an SQL node already be connected to the cluster at
the time that a database is created on another SQL node,
or for a CREATE DATABASE or
CREATE
SCHEMA statement to be issued on the new SQL
node after it joins the cluster.

Multiple data node processes per host.
In earlier MySQL Cluster release series, we did not
support MySQL Cluster deployments in production where more
than one ndbd process was run on a
single physical machine. However, beginning with MySQL
Cluster NDB 6.2.0, you can use multiple data node
processes on a single host.

Improved Disk Data file system configuration.
As of MySQL Cluster NDB 6.2.17, you can specify default
locations for MySQL Cluster Disk Data data files and undo
log files using the data node configuration parameters
FileSystemPathDD,
FileSystemPathDataFiles,
and
FileSystemPathUndoFiles.
This eliminates the need to use symbolic links to place
Disk Data files separately from other files in data node
file systems to improve Disk Data performance. For more
information, see
Disk Data file system parameters.

Automatic creation of Disk Data log file groups and tablespaces.
Beginning with MySQL Cluster NDB 6.2.17, using the data
node configuration parameters
InitialLogFileGroup
and
InitialTablespace,
you can cause the creation of a MySQL Cluster Disk Data
log file group, tablespace, or both, when the cluster is
first started. When using these parameters, no SQL
statements are required to create these Disk Data objects.

Improved access to partitioning information.
The ndb_desc utility now provides
additional information about the partitioning of data
stored in MySQL Cluster. Beginning with MySQL Cluster NDB
6.2.19, the
--extra-node-info option
causes ndb_desc to include information
about data distribution (that is, which table fragments
are stored on which data nodes). This option also requires
the use of the
--extra-partition-info
option.

Information about partition-to-node mappings can also be
obtained using the
Table::getFragmentNodes()
method, also added in MySQL Cluster NDB 6.2.19.

New CHANGE MASTER TO option for circular replication.
Beginning with MySQL Cluster NDB 6.2.19, the
CHANGE MASTER TO statement
supports an IGNORE_SERVER_IDS option
which takes a comma-separated list of server IDs and
causes events originating from the corresponding servers
to be ignored. (Log rotation and log deletion events are
preserved.)